Process Of Thermal Transfer Using Hot Melt Adhesive Lamination For Forming A Carpet Backing And Finished Carpet Or Tile Product

ABSTRACT

A method for binding a greige carpet and a secondary backing material using a hot melt adhesive is disclosed. A heated application roll may be provided and the secondary backing material may be contacted with the hot melt adhesive and greige carpet and pressed against the heated application roll.

This application is a continuation of U.S. patent application Ser. No.11/242,133, filed Oct. 4, 2005, entitled, “Process of Thermal TransferUsing Hot Melt Adhesive Lamination for Forming a Carpet Backing andFinished Carpet or Tile Product,” the disclosure of which isincorporated herein by reference in its entirety. This application alsoclaims priority to provisional application serial No. 60/614,966, filedOct. 4, 2004, entitled, “Process of Thermal Transfer Using Hot MeltAdhesive Lamination for Forming a Carpet Backing and Finished Carpet orTile Product,” the disclosure of which is incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

Embodiments of the invention relate generally to finishing systems fortufted primary backing carpets and more specifically to systems thatbind greige carpet and secondary backing material using hot meltadhesives.

DESCRIPTION OF RELATED ART

The primary component of conventional broadloom carpet products such ascarpet tiles is tufted “greige” carpet. Greige carpet generallycomprises fiber tufts looped around a primary backing fabric. Primarybacking fabrics may be woven, nonwoven, or spun bonded natural orsynthetic materials. The tufted loops of fiber may be left intact orsheared so that the upright face fibers, or pile, are left with randomends facing outwards on the visible wear surface, or face side, of thecarpet.

In order to more permanently secure the fiber tufts looped around theprimary backing fabric and provide dimensional stability to the finishedproduct, secondary backing materials may be applied to the back side ofthe greige carpet.

Common secondary backing materials include latex, urethanes, thermalplastics such as PVC, and modified olefin-based thermal formableplastics. Additionally, woven materials such as oriented polypropylene,polyesters, jute, and other nonwoven felted type materials may be usedas secondary backing materials. A variety of additives intended toimpart other desirable characteristics to the finished carpet, includingresistance to fuzzing (individual fibers pulling loose during usage),moisture impermeability, fire retardency, sound absorbency, andantibacterial properties also may be added as secondary backingmaterials.

Secondary backing materials may be secured to the greige carpet using,for example, a hot melt adhesive. Additionally, hot melt adhesives mayperform other beneficial functions when applied to greige carpet. Forexample, if the hot melt adhesive is able to penetrate into the fibertufts during application, then the adhesive may help secure the fibertufts to the primary backing material and prevent fuzzing. Also, hotmelt adhesives may impart additional mechanical strength to the greigecarpet.

For example, U.S. Pat. No. 6,503,595, the disclosure of which isincorporated herein by reference in its entirety, discloses a carpetthat includes a primary backing having tufts of synthetic carpet fibersprotruding from a top surface and, optionally, a secondary backing withan extruded sheet of a polyolefin polymer between the primary andsecondary backing. The polyolefin sheet adheres to the primary andsecondary backings, thereby fusing the two together.

In order to facilitate the penetration of the hot melt adhesive into thetufted fiber bundles of the greige carpet, it may be desirable to chosean adhesive that has a low viscosity but at a relatively lowtemperature. However, such an adhesive often does not have adequatemechanical strength to impart dimensional stability to the greigecarpet. Conversely, mechanically stronger adhesives often attain lowviscosity only at higher temperatures, necessitating application of theadhesive at higher temperatures. Higher process temperatures may causethe greige carpet to shrink and may damage the primary backing materialand fiber tufts, resulting in a loss of finished carpet and increasedmanufacturing costs. The dichotomy between low viscosity and lowapplication temperature sometimes makes application of hot meltadhesives difficult.

Several methods have been utilized in an attempt to overcome thedifficulties associated with applying hot melt adhesives to greigecarpet and secondary backing materials.

For example, in order to avoid higher process temperatures andassociated damage to the greige carpet, hot melt adhesives with higherviscosities (and therefore greater mechanical strength) may be appliedto a greige carpet and pressed into the fiber tufts by means of highpressures. For example, the greige carpet may be coated with a hot meltadhesive that is heated but only to a temperature sufficiently low toavoid damaging the greige carpet. The hot melt adhesive coated greigecarpet then is nipped at high pressure. Nipping at pressures, however,may result in distortion of the carpet because of the flattening of thefiber tufts at the face side of the carpet.

For example, U.S. Pat. App. No. 2002/0193474, the disclosure of which isincorporated herein by reference in its entirety, discloses a modifiedhot melt adhesive which is applied in an extruded form. The hot meltbacking is nipped under high pressure against a cool roller, therebyflattening and cooling the yarn loops.

Additionally, U.S. Pat. No. 4,576,665, the disclosure of which isincorporated herein by reference in its entirety, provides a hot meltadhesive bonded pile fabric that comprises a liquid permeable base layerand a pile forming yarn adjacent to the base layer but not tuftedthrough the base layer, the pile forming element having been bonded tothe base layer by means of a hot melt adhesive applied to the back ofthe base layer. The hot melt adhesive applied to the back of the baselayer is forced through the permeable base layer using an applicatorroll to apply pressure.

Alternatively, U.S. Pat. No. 3,962,012, the disclosure of which isincorporated herein by reference in its entirety, teaches a process forlaminating a primary and a secondary sheet that seeks to avoid damagingthe face side of the primary sheet by applying an adhesive to the backside of the primary sheet or to the mating side of the secondary sheet,or to both, contacting the mating side of the secondary sheet with theback side of the primary sheet, and firmly pressing together the twosheets while avoiding the application of any pressure to thepressure-sensitive face side of the primary sheet until at least 50percent of the terminal bond strength is developed. The two sheets arefirmly pressed together by maintaining the primary and secondary sheetstaut and applying pressure from the back side of the secondary sheet.

Instead of the use of pressure, the hot melt adhesives may be applied athigher temperatures so that the adhesive is less viscous. This may beaccomplished, for example, using heated lamination rolls. However,heated lamination rolls are often sullied by loose fibers that adhere tothe roll, therefore necessitating shut down for cleaning.

In another alternative, multi-layered hot melt adhesives may beutilized. One of the layers is typically a low-melting point adhesivethat easily infiltrates the fiber tufts attached to the primary backingmaterial. The other layer is typically a high-melting point adhesivethat imparts additional mechanical strength to the greige carpet.Forming a multi-layered hot melt adhesive, however, may introduceadditional complexity and cost into the manufacturing process.

For example, WO 2004/025018, the disclosure of which is incorporatedherein by reference in its entirety, describes a process for marrying asecondary backing material with an unfinished tufted primary carpetusing a hot melt adhesive. The hot melt adhesive comprises two adhesivelayers applied by contiguous extrusion—a lower viscosity layer to lockthe fibers in place and a higher viscosity layer to thicken and flattenthe entire adhesive coating. The lower viscosity layer of hot meltadhesive is intended to be pressed into and around the fiber roots.

Another method to apply hot melt adhesives is to pre-form an adhesivelayer before applying the adhesive layer to the greige carpet andsecondary backing material. Again, pre-forming an adhesive layer mayintroduce additional complexity and cost in the manufacturing process.

For example, U.S. Pat. No. 6,479,125, the disclosure of which isincorporated herein by reference in its entirety, teaches the productionof a finished carpet employing a multitude of layers. A heated film ofthermofusible bonding material with a lower melting point than that ofthe primary carpet and backing materials is used to encapsulate thelayers without excessively heating the fibers or layers themselves.However, the film must be preformed in order to have consistent weightdistribution across the carpet.

U.S. Pat. No. 4,844,765, the disclosure of which is incorporated hereinby reference in its entirety, teaches the lamination of a tufted primarycarpet into a finished product with the use of hot melt adhesive insheet form. The sheet of hot melt adhesives is preformed andsubsequently laminated between the unfinished primary tufted carpet andthe secondary backing while at an elevated temperature.

Several other patents teach other methods to produce finished broadloomcarpet using hot melt adhesives. For example, U.S. App. No.2003/0211280, the disclosure of which is incorporated herein byreference in its entirety, provides a method of making a carpetcomprising a greige carpet and an adhesive backing material. Theadhesive backing material is applied to the greige carpet by extrusioncoating and at least one additional step selected from (a) preheatingthe greige good prior to the application of the adhesive backingmaterial, (b) subjecting the adhesive backing material to a vacuum todraw the adhesive backing material onto the back side of the primarybacking material, (c) subjecting the adhesive backing material to apositive air pressure device in addition to nip roll pressure to forcethe adhesive backing material onto the back side of the primary backingmaterial, and (d) heat soaking the carpet after application of theadhesive backing material onto the back side of the primary backingmaterial.

The description herein of problems and disadvantages of known apparatus,methods, and compositions is not intended to limit the invention to theexclusion of these known entities. Indeed, embodiments may include oneor more of the known apparatus, methods, and compositions withoutsuffering from the disadvantages and problems noted herein.

SUMMARY OF THE EMBODIMENTS

It therefore would be desirable to bind a greige carpet with a secondarybacking material using a hot melt adhesive in a single-pass process thatprovides for excellent penetration of the hot melt adhesive into theyarn fiber tufts of the greige carpet while minimizing shrinkage andgeneral deterioration of the greige carpet.

It also would be desirable to provide a process of making a secondarybacking material the provides improved fire retardancy for the carpetmaterial, and preferably so that the carpet materials pass a Class 1fire rating.

Therefore, in accordance with one embodiment, there is provided a methodfor binding a greige carpet with a secondary backing material using ahot melt adhesive. The method provides for a heated application roll.The hot melt adhesive may be applied to the secondary backing materialto form an adhesive-loaded secondary backing material. Theadhesive-loaded secondary backing material then can be contacted withthe heated application roll to form a secondary backing material on theheated application roll. The greige carpet preferably is pressed againstthe secondary backing material on the heated application roll to form afinished carpet.

In accordance with another embodiment, there is provided an apparatusfor producing carpet. The apparatus comprises a heated application roll;a means for providing a greige carpet to the heated application roll; ameans for providing a secondary backing material to the heatedapplication roll, the means being positioned upstream of the heatedapplication roll from the means for providing the greige carpet; a meansfor providing a hot melt adhesive to the secondary backing material; atleast one unheated nip roll positioned adjacent to the heatedapplication roll where the greige carpet first contacts the heatedapplication roll; a chill roll positioned downstream from the heatedapplication roll; an idler tension roll positioned adjacent to the chillroll; and a means for collecting a finished carpet positioned downstreamfrom the chill roll.

Still further features and advantages of the present invention areidentified in the ensuing description, with reference to the drawingsidentified below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of an exemplary apparatus for the productionof carpet.

FIG. 2 is another illustration of an exemplary apparatus for theproduction of the carpet.

FIG. 3, embodiments A and B, are illustrations of an exemplaryconfiguration of the heated application roll and two unheated adjustablenip rolls positioned adjacent to the heated application roll.

FIG. 4 is an illustration of an exemplary means for providing a hot meltadhesive.

FIG. 5 is an illustration of an exemplary configuration of the chillroll.

DETAILED DESCRIPTION OF THE INVENTION

The following description is intended to convey a thorough understandingof the embodiments by providing a number of specifically preferredembodiments and details involving the binding of greige carpet andsecondary backing materials using hot melt adhesives. It is understood,however, that the invention is not limited to these specific embodimentsand details, which are exemplary only. It is further understood that onepossessing ordinary skill in the art, in light of known systems andmethods, would appreciate the use of the invention for its intendedpurposes and benefits in any number of alternative embodiments.

One embodiment is a method for binding a greige carpet comprising a faceside and a back side with a secondary backing material using a hot meltadhesive. The hot melt adhesive can be applied to the secondary backingmaterial to form an adhesive-loaded secondary backing material. Theadhesive-loaded secondary backing material then can be contacted with aheated application roll to form a secondary backing material on theheated application roll. The back side of the greige carpet thenpreferably is pressed against the secondary backing material on theheated application roll to form a finished carpet.

The greige carpet may comprise, for example, a primary backing fabricand fiber tufts wound around the primary backing fabric. The fiber tuftsmay be composed of any applicable material. However, the fiber tuftspreferably are composed of nylon, polyester, acrylic, rayon, polyolefinssuch as polypropylene, polyethylene, etc., wool, or cotton fibers, andcombinations or mixtures thereof. The backing material likewise may becomposed of any applicable material. Preferred compositions of theprimary backing material include, but are not limited to, nonwoven orwoven polyesters, polypropylene, nylon fabrics, and combinations ormixtures thereof. Additionally, the primary backing material maycomprise straight stitched, side stitched, cross stitched, or otherwoven fabrics that are difficult for the hot melt adhesive to penetratein traditional binding processes.

The secondary backing material also may be composed of any applicablematerial, in accordance with the principles of the invention. Woven ornonwoven polyester, polypropylene, nylon-coated polyester fibers, andcombinations or mixtures thereof are preferred materials for thesecondary backing material. Single layer and multi-layered secondarybacking materials may be used in embodiments of the invention. Athermoset polyester is a more preferred material for use as thesecondary backing material. A woven textile with thread counts between10 and 200 threads per inch in both the warp and weft directions isanother preferred material for use as the secondary backing material.Even more preferred is a woven secondary backing material with a threadcount between 20 and 80 threads per inch in both the warp and weftdirections.

It may be desirable that the secondary backing material be resistant todimensional distortion at higher temperatures. Therefore, a secondarybacking material that exhibits dimensional thermal stability attemperatures up to 350° F. is preferred. Dimensional thermal stabilitymeans that the secondary backing material shrinks less than 5% each inthe warp and weft directions at that temperature.

The hot melt adhesive also may be any applicable hot melt adhesive. Oneskilled in the art will recognize the many different hot melt adhesivesthat are applicable in the manufacture of carpet materials, using theguidelines provided herein. Preferred hot melt adhesives are esters ofpolyethylene terephthalate (PET) and a modifying polymer. Otherpreferred hot melt adhesives are esters of polyethylene naphthalate(PEN) and a modifying polymer. The modifying polymer, for example, maybe one or more of polyethylene glycol, diethylene glycol, trimethylolpropane, phthalic anhydride, adipic acid, and combinations or mixturesthereof. Additionally, esterification catalysts may be added to themixture in order to promote esterification of the modifying polymers andtrans-esterification with PET and PEN. For example, a mixture of 3.63%by weight of polyethylene glycol, 1.82% diethylene glycol, 17.20%trimethylol propane, 12.29% adipic acid, 0.08% Fascat® 4100esterification catalyst (commercially available from Atofma Chemicals,Inc., Philadelphia, Pa.), 0.02% Tyzor® TPT trans-esterification catalyst(commercially available from Dupont, Wilmington, Del.), and 64.96% PETis a preferred mixture of modifying polymers, PET, and esterificationcatalysts that may be used as a hot melt adhesive. Another preferredmodified PET hot melt adhesive would include PET and a combination ofoleic acid, adipic acid, trimethylol propane, PEG, diethylene glycol,Fascat® 4100 esterification catalyst (commercially available fromAtofina Chemicals, Inc., Philadelphia, Pa.), hydroquinone, and BNX® 1225(an antioxidant commercially available from Mayzo Chemicals, Norcross,Ga.). Suitable hot melt adhesives prepared from modified PET and PEN aredisclosed in U.S. application Ser. No. 10/827,028 filed on Apr. 19,2004, entitled: “Polymer Manufacturing Process,” attorney docket number62136.000051, the disclosure of which is incorporated by referenceherein in its entirety.

The hot melt adhesive may be mixed with additives to impart additionalbeneficial qualities to the finished carpet. Applicable additivesinclude, but are not limited to, fire retardants, fillers such asmagnetite and other fillers, weighters, oxidization stabilizers,antibacterial agents, antimicrobial agents, antifungal agents, UVstabilizers, and combinations or mixtures thereof. One skilled in theart will recognize other applicable additives that may optionally beadded to the hot melt adhesive, in accordance with the guidelinesprovided herein.

Inclusion of sufficient fire retardant to satisfy Class 1 firestandards, particularly in reference to commercial applications of thefinished carpet, is a more preferred additive to the hot melt adhesive.Any fire retardant can be used. For example, a fire retardant may beadded in large concentrations so as to attain a Class 1 fire rating.Because the embodiments described herein may be less susceptible tochanges in the viscosity of the hot melt adhesive, for example changesin viscosity as a result of the inclusion of additives in the hot meltadhesive mixture, greater amounts of additives may be added than hassometimes traditionally been the case.

Nevertheless, lower viscosity hot melt adhesives may more fullypenetrate the fiber tufts of the greige carpet. Therefore, it ispreferred that the hot melt adhesive have a viscosity of less that250,000 centipoise 325° F. More preferred is a hot melt adhesive thathas a viscosity of less 50,000 centipoise at 325° F.

The hot melt adhesive preferably is applied to the secondary backingmaterial to form an adhesive-loaded secondary backing material. Applyingthe hot melt adhesive to the secondary backing material may take placein any applicable manner. For example, the hot melt adhesive may besprayed or rolled on the secondary backing material. The hot meltadhesive may be applied in one application, or multiple applications toprovide a multi-coated secondary backing material.

In a preferred method for applying the hot melt adhesive to thesecondary backing material, a heated doctor bar may be positionedgenerally above the point of contact between the secondary backingmaterial and the heated application roll in order to regulate the amountof hot melt adhesive that is contacted with the secondary backingmaterial. The heated doctor bar may cause a puddle of hot melt adhesiveto form on and seep into the secondary backing material. In this way,the heated doctor bar may apply a smooth, continuous, and highlyconcentrated layer of hot melt adhesive to the secondary backingmaterial in a single application.

Coating weights of 120 ounces of hot melt adhesive per square yard ofsecondary material are traditionally difficult to attain. Higher coatingweights, for example about 240 ounces of hot melt adhesive per squareyard of secondary material, however, may be attainable throughembodiments of the invention. A coating weight of between 4 and 240ounces of hot melt adhesive per square yard of secondary backingmaterial is preferred, more preferably the coating weight is within therange of from about 80 to about 240 ounces per square yard, and mostpreferably from about 120 to about 240 ounces per square yard. This maybe advantageous because increased concentrations of hot melt adhesivemay aid in securing together the greige carpet and secondary backingmaterial, thereby preventing delamination of the finished carpet.Additionally, achieving a high coating weight of hot melt adhesive in asingle application step may eliminate the need to apply the hot meltadhesive in multiple steps. The position of the heated doctor bar may bevariable in order to allow a variable amount of hot melt adhesive to beapplied to the secondary backing material.

The hot melt adhesive may be delivered to the doctor bar or blade by,for example, a heated extrusion die extending the width of the heatedapplication roll. Because the extrusion die extends the width of theheated application roll, a more uniform application of hot melt adhesiveacross the width of the secondary backing material may occur.

The hot melt adhesive may be heated during application to the secondarybacking material in order to attain a lower viscosity. A lower viscositymay be advantageous because, at lower viscosities, the hot melt adhesivemay more easily penetrate the secondary backing material. For example,the hot melt adhesive may be heated in a heating vessel before beingextruded through the heated extrusion die and delivered to the heateddoctor bar. Because the extrusion die and doctor bar both are heated,the hot melt adhesive is less likely to cool significantly beforeapplication to the secondary backing material.

Additionally, because the heated hot melt adhesive may emit toxic fumes,a vacuum may be drawn on the hot melt adhesive in order to capture thefumes.

The temperature to which the hot melt adhesive is warmed may be chosento be low enough so as to avoid degradation of the fiber tufts of thegreige carpet and dimensional distortion of the greige carpet that mightoccur at temperatures that are too high. One skilled in the art willappreciate that the choice of temperature to which the hot melt adhesivemay be warmed will be dictated, in part, by the choice of greige carpet,secondary backing material, and hot melt adhesive.

The adhesive-loaded secondary backing material preferably is contactedwith the heated application roll to form a secondary backing material onthe heated application roll. Heating the application roll helps tomaintain the elevated temperature of the hot melt adhesive, therebyaiding the penetration of the adhesive into the secondary backingmaterial. Additionally, because the greige carpet is contacted with thesecondary backing material on the heated application roll, the greigecarpet also may be warmed by the heated application roll. Warming thegreige carpet also may aid the hot melt adhesive in penetrating thegreige carpet.

Increased penetration of the hot melt adhesive into the secondarybacking material and the greige carpet may result in increased adhesionbetween the two layers. Therefore, multi-layer adhesives may not berequired in the embodiments described herein, in order to achieve thedesired level of adhesion. Also, increased penetration of the hot meltadhesive into the secondary backing material and the greige carpet mayimpart additional mechanical strength to the finished carpet, therebynegating the need to apply additional stabilization layers, for examplefiberglass backings, to strengthen the finished carpet. Increasedpenetration of the hot melt adhesive into the greige carpet also mayhelp prevent fuzzing of the tufted fibers during use. Furthermore,increased penetration of the hot melt adhesive may reduce or eliminatethe need to force the hot melt adhesive into the greige carpet orsecondary backing material by means of pressure, thereby reducing thepossibility of the fiber tufts being flattened or crushed underpressure.

Finally, heating the greige carpet and secondary backing materials mayhelp to reduce the ‘heat sink’ effect of contacting the warm hot meltadhesive with a cool secondary backing material or greige carpet, whichwould lower the temperature of the hot melt adhesive and deteriorate theflow characteristics of the adhesive. Therefore, the hot melt adhesivemay be applied to the secondary backing material at a lower temperaturethan would be required if the greige carpet and secondary backingmaterial were not heated, thereby reducing the possible distortingeffect of the warm hot melt adhesive on the greige carpet. One skilledin the art will appreciate other beneficial effects of heating thegreige carpet and secondary backing material by the heated applicationroll.

If desired, the greige carpet may be separately heated before pressingagainst the secondary backing material on the heated application roll.This may be accomplished, for example, by radiant or infrared heating ofthe back side of the greige carpet before pressing against the secondarybacking material on the heated application roll. One skilled in the artwill recognize other ways in which the greige carpet may be heated priorto pressing against the secondary backing material on the heatedapplication roll.

The back side of the greige carpet preferably is pressed against thesecondary backing material on the heated application roll to form afinished carpet. It is preferred that a first and second unheated niproll adjacent to the heated application roll press the greige carpetagainst the secondary backing material on the heated application roll inorder to effect contact between the two. Additionally, the first andsecond unheated nip rolls adjacent to the heated application roll maytightly draw the secondary backing material against the heatedapplication roll. The first and second unheated nip rolls may bepositioned immediately adjacent to the heated application roll andpreferably may be adjustable. In one preferred embodiment, for example,the first and second unheated nip rolls adjacent to the heatedapplication roll are adjusted so that the nip rolls press the greigecarpet against the secondary backing material for at least 80% of theheated application roll's surface area. In another preferred embodiment,the first and second unheated nip rolls adjacent to the heatedapplication roll are adjusted so that the nip rolls press the greigecarpet against the secondary backing material for less 80% of the heatedapplication roll's surface area. The first and second unheated nip rollsadjacent to the heated application roll may press against the face sideof the greige carpet, therefore pressing the back side of the greigecarpet against the secondary backing material on the heated applicationroll.

Because the greige carpet is pressed against the secondary backingmaterial, the greige carpet may never come into direct contact with theheated application roll. This is desirable in order to avoid loose fibertufts from the primary backing fabric adhering to the heated applicationroll, which might necessitate periodic cleaning of the heatedapplication roll or possible shut down.

Because the finished carpet may be at an elevated temperature uponexiting the heated application roll, it may be desirable to contact thefinished carpet with a chill roll in order to cool the finished carpetand solidify the hot melt adhesive. The finished carpet product may becontacted with the chill roll, for example, by means of an idler tensionroll adjacent to the chill roll. The idler tension roll preferably islocated a sufficient distance from the chill roll such that fiber tuftsthat may have been flattened by the idler tension roll may primarilyre-orient themselves in the position perpendicular to the primarybacking fabric of the finished carpet before contacting the chill roll.By “primarily,” it is meant than at least 80%, more preferably 90%, andmost preferably 95% of the fiber tufts that might have been flattened bythe idler tension roll will re-orient in the position perpendicular tothe primary backing fabric of the finished carpet. One skilled in theart will appreciate that other methods by which the finished carpet maybe cooled and other alternative configurations of the chill roll may bepracticed in accordance with the present invention, in accordance withthe guidelines provided herein.

It may be desirable to wind the finished carpet around a means forcollecting the finished carpet. The means, for example, may be a finalroll, intermediate roll, or other collection mechanism. When anappropriate amount of finished carpet is wound around the final roll,the carpet is cut and the final roll removed and replaced by anotherfinal roll, around which more finished carpet then is wound. Other rollspositioned between the chill roll and final roll may make the finishedcarpet taut during winding around the final roll. It is preferred thatthe finished carpet be made taut during winding around the final roll inorder to maximize the amount of finished carpet that may be wound aroundthe final roll, and to cause the fiber tufts to orient in theperpendicular direction relative to the primary backing fabric of thefinished carpet.

If desired, the finished carpet may be cut into carpet tiles andcollected as an alternative to the collection means. Alternatively, thefinished carpet may be un-wound from the collection means at a latertime and cut into carpet tiles.

FIG. 1 illustrates an exemplary apparatus for the production of carpetaccording to a preferred embodiment. A means for providing a greigecarpet 1, for example, may include a roll of greige carpet 13. Likewise,a means for providing a secondary backing material 2, for example, mayinclude a roll of secondary backing material 14. In an alternativeembodiment not shown, the greige carpet and secondary backing materialmay be provided directly from a process for producing the greige carpetor secondary backing material.

A hot melt adhesive 3 preferably is provided by a heated extrusion die11 extending the width of a heated application roll 4. The hot meltadhesive 3 preferably is applied to the secondary backing material 2 toform an adhesive-loaded secondary backing material, for example, using aheated doctor bar 10 that confines the hot melt adhesive 3 and aids inforcing the hot melt adhesive to penetrate into the secondary backingmaterial 2. For example, a puddle of hot melt adhesive 16 may form infront of the heated doctor bar from which the hot melt adhesive 3 seepsinto the secondary backing material 2.

The adhesive-loaded secondary backing material preferably is broughtinto contact with the heated application roll 4, for example, by meansof first and second unheated nip rolls 5 adjacent to the heatedapplication roll to form a secondary backing material on the heatedapplication roll. The greige carpet product 1, also may be pressedagainst the secondary backing material on the heated application roll toform a finished carpet 6 by means of the first and second unheated niprolls 5 adjacent to the heated application roll 4.

The finished carpet 6 can be withdrawn from the heated application roll4 and conveyed to a chill roll 12 by the second unheated nip roll 5 anda idler tension roll 7. The idler tension roll 7 preferably ispositioned at a sufficient distance from the chill roll 12 so that thefiber tufts of the finished carpet will not primarily be flattened whenthey come into contact with the chill roll 12, meaning that at least80%, more preferably at least 90%, and most preferably at least 95% ofthe fiber tufts that may have been flattened by the idler tension roll 7will be re-oriented in the direction perpendicular to the primarybacking fabric of the finished carpet 6 before coming into contact withthe chill roll 12. The chill roll 12 may cool the finished carpet inorder to, for example, set the holt melt adhesive. The finished carpetthen preferably is wound around a final roll 15. Other rolls 13 mayguide and make the finished carpet taut as it is wound around the finalroll 15.

FIG. 2 illustrates an alternative apparatus for the production of carpetwith one unheated nip roll 5. Like numeral elements of FIG. 2 correspondto the elements identified in reference to FIG. 1.

Referring now to FIG. 3, embodiment A, the first and second unheated niprolls 22 adjacent to the heated application roll 21 are adjustable. Theadhesive-loaded secondary backing material 23 is pressed against theheated application roll 21 by the unheated nip rolls 22 to form asecondary backing material on the heated application roll. The greigecarpet 24 also is pressed against the secondary backing material on theheated application roll by the unheated nip rolls 22 to form a finishedcarpet 20. The finished carpet 20 also is pressed against the heatedapplication roll 21 by the unheated nip rolls 22. Because the unheatednip rolls 22 are adjustable, the area of the heated application roll 21against which the finished carpet 20 is pressed can be varied.

Embodiment B of FIG. 3 illustrates an alternative configuration of thetwo unheated nip rolls 22. In this embodiment, the unheated nip rolls 22have been adjusted toward the bottom of the heated application roll 21.Adjusting the nip rolls 22 in this way reduces the surface area of theheated application roll 21 over which the finished carpet 20 is pressedagainst the heated application roll 21. It should be understood that theunheated nip rolls 22 may be positioned anywhere around the heatedapplication roll 21, not just at the two exemplary positions illustratedin FIG. 3, embodiments A and B.

FIG. 4 depicts in greater detail an exemplary means for providing thehot melt adhesive 32 to the secondary backing material 30. The adhesiveis heated in a heating vessel 38. A vacuum source 37 applies a vacuum tothe heated hot melt adhesive in order to remove volatile vapors that maybe released by the heated hot melt adhesive during heating. The adhesivepreferably is spread by a heated extrusion die 36 the width of theheated application roll 33. A heated doctor bar 35 preferably capturesthe stream of hot melt adhesive 32, forming a puddle 39 of hot meltadhesive in front of the heated doctor bar 35. This aids the hot meltadhesive in penetrating the secondary backing material 30 to form anadhesive-loaded secondary backing material. The adhesive-loadedsecondary backing material and greige carpet 31 then may be pressedagainst one another and brought into contact with the heated applicationroll 33 by means of the first and second unheated nip rolls 34. Thoseskilled in the art will appreciate that other means for providing thehot melt adhesive may be used, including, for example, extruders, andthe like.

FIG. 5 depicts in greater detail an exemplary configuration of the idlertension roll 44 and chill roll 43. The idler tension roll 44 is asufficient distance from the chill roll 43 so that the fiber tufts 42 ofthe finished carpet 40 are able to re-orient themselves into a directionperpendicular to the primary backing fabric 45 of the finished carpetbefore coming into contact with the chill roll 43. In this way, thefiber tufts of the finished carpet are less likely to be in a flattenedposition when the hot melt adhesive is cooled and set. Otherwise, if thehot melt adhesive is cooled when the fiber tufts are in a flattenedposition, the fiber tufts may be locked into that position, resulting ina general degradation of the quality of the finished carpet. Other rolls46 may guide the finished carpet 40 away from the chill roll 43following contacting.

The invention now will be described in more detail with reference to thefollowing non-limiting examples.

EXAMPLE 1

Beaulieu straight stitched greige carpet type, 24 inches wide wasprovided. Secondary backing material comprising heat set PET wovenfibers with 45 threads per inch count in both the warp and weftdirections was also provided (commercially available from AliceManufacturing). Hot melt adhesive produced from PET modified with amodifying formulation in accordance with U.S. application Ser. No.10/827,028 filed on Apr. 19, 2004, was provided. The hot melt adhesivehad a viscosity of 35 centipoise at 325° F. and was mixed at equal partsper weight with a magnetite filler. The heating vessel and heatedextrusion die were heated to 325° F. The heated application roll andheated doctor bar were heated to 335° F. The heated doctor bar was set65 thousandths of an inch from the surface of the secondary backingmaterial. The first unheated nip roll was set at a 250 thousandths of aninch gap from the heated application roll. The second unheated nip rollwas set at a 90 thousandths of an inch gap from the heated applicationroll. The idler tension roll was set at a ¾ inch gap from the chillroll. The chill roll temperature was set at 70° F. The greige carpet andsecondary backing material were fed to the application roll at a speedof 10 feet per minute. Wind-up roll tension was set at 3 pounds perlinear inch.

EXAMPLE 2

Beaulieu straight stitched greige carpet type, 24 inches wide wasprovided. Secondary backing material comprising heat set PET wovenfibers with 45 threads per inch count in both the warp and weftdirections was also provided (commercially available from AliceManufacturing). The hot melt adhesive described in Example 1 was used.The hot melt adhesive had a viscosity of 30 centipoise at 325° F. andwas mixed at equal parts per weight with the same magnetite filler usedin Example 1. The heating vessel and heated extrusion die were heated to335° F. The heated application roll and heated doctor bar were heated to340° F. The heated doctor bar was set 65 thousandths of an inch from thesurface of the secondary backing material. The first unheated nip rollwas set at a 250 thousandths of an inch gap from the heated applicationroll. The second unheated nip roll was set at a 90 thousandths of aninch gap from the heated application roll. The idler tension roll wasset at a % inch gap from the chill roll. The chill roll temperature wasset at 60° F. The greige carpet and secondary backing material were fedto the application roll at a speed of 10 feet per minute. Wind-up rolltension was set at 3 pounds per linear inch.

EXAMPLE 3

Beaulieu straight stitched greige carpet type, 24 inches wide wasprovided. Secondary backing material comprising heat set PET wovenfibers with 45 threads per inch count in both the warp and weftdirections also was provided (commercially available from AliceManufacturing). The hot melt adhesive described in Example 1 was used.The hot melt adhesive had a viscosity of 25 centipoise at 325° F. andwas mixed at equal parts per weight with the same magnetite filler usedin Example 1. The heating vessel and heated extrusion die were heated to325° F. The heated application roll and heated doctor bar were heated to330° F. The heated doctor bar was set 65 thousandths of an inch from thesurface of the secondary backing material. The first unheated nip rollwas set at a 250 thousandths of an inch gap from the heated applicationroll. The second unheated nip roll was set at a 90 thousandths of aninch gap from the heated application roll. The idler tension roll wasset at a ¾ inch gap from the chill roll. The chill roll temperature wasset at 70° F. The greige carpet and secondary backing material were fedto the application roll at a speed of 10 feet per minute. Wind-up rolltension was set at 3 pounds per linear inch.

The peel strength of the finished carpet produced in Examples 1-3 was sogreat that during testing destruction of the finished carpet occurredbefore delamination of the greige carpet and secondary backing material.It is thought that the penetration of the hot melt adhesive into thesecondary backing material during application to the secondary backingmaterial helps to achieve the great peel strength. Peel strength is animportant quality of the finished carpet because, if the greige carpetand secondary backing material delaminates during use, then the greigecarpet might peel loose from the secondary backing material that isfixed to the floor.

Embodiments of the invention provide a method of making a carpet tilewithout having to apply multiple coats of adhesive, and withoutsignificantly damaging the tufts of the carpeting material.

The high coating weights of hot melt adhesive achievable throughpracticing the embodiments also may avoid the necessity of applyingmultiple hot melt adhesive layers to achieve a given coating weight,thereby lowering manufacturing costs.

Additionally, practicing the embodiments may produce carpet wherein thefiber tufts are less likely to be in a non-perpendicular positionrelative to the primary backing fabric of the finished carpet. This mayresult in a generally higher-grade carpet product.

The embodiments have been described with reference to particularlypreferred embodiments and examples. Those skilled in the art willappreciate that various modifications may be made to the inventionwithout departing from the spirit and scope thereof.

1. A method for binding a greige carpet comprising a face side and aback side with a secondary backing material using a hot melt adhesive,comprising: providing a heated application roll; applying the hot meltadhesive to the secondary backing material to form an adhesive-loadedsecondary backing material; providing a heated doctor bar disposedgenerally over the point of contact between the secondary backingmaterial and the heated application roll; contacting the adhesive-loadedsecondary backing material with the heated application roll to form asecondary backing material on the heated application roll; and pressingthe greige carpet against the secondary backing material on the heatedapplication roll to form a finished carpet.
 2. The method of claim 1,wherein the greige carpet comprises fiber tufts looped around a primarybacking fabric.
 3. The method of claim 2, wherein the fiber tufts areselected from the group consisting of nylon, polyesters, acrylics,rayon, cotton fibers, and combinations or mixtures thereof.
 4. Themethod of claim 2, wherein the primary backing fabric is selected fromthe group consisting of nonwoven and woven polyesters, polypropylene,nylon fabrics, and combinations or mixtures thereof.
 5. The method ofclaim 1, wherein the secondary backing material is selected from thegroup consisting of woven and nonwoven polyester, polypropylene,nylon-coated polyester fibers, and combinations or mixtures thereof. 6.The method of claim 5, wherein the secondary backing material is athermoset polyester.
 7. The method of claim 1, wherein the secondarybacking material is a woven textile with thread counts between 20 and 80threads per inch in both the warp and weft directions.
 8. The method ofclaim 1, wherein the secondary backing material exhibits dimensionalthermal stability at temperatures up to 350° F.
 9. The method of claim1, wherein the hot melt adhesive is selected from esters of polyethyleneterephthalate and a modifying polymer, or esters of polyethylenenaphthalate and a modifying polymer.
 10. The method of claim 9, whereinthe modifying polymer is selected from the group consisting ofpolyethylene glycol, diethylene glycol, trimethylol propane, phthalicanhydride, oleic acid, adipic acid, and combinations or mixturesthereof.
 11. The method of claim 8, wherein the hot melt adhesiveadditionally comprises an additive selected from the group consisting offire retardants, fillers, weighters, oxidization stabilizers,antibacterial agents, antimicrobial agents, antifungal agents, UVstabilizers, and combinations or mixtures thereof.
 12. The method ofclaim 1, wherein applying the hot melt adhesive comprises applying theadhesive at a coating weight of from about 4 to about 240 ounces of hotmelt adhesive per square yard of secondary backing material.